diff --git a/Makefile b/Makefile
index 9f5d8b59..d0612104 100644
--- a/Makefile
+++ b/Makefile
@@ -36,7 +36,7 @@ SUBDIRS = inst/pre \
 		YCbContr YThread \
 		YStopWatchList YStopWatchQueue YStopWatchThreadList \
 		YApplication \
-		YOsc \
+		YOsc os \
 		lib include bin \
 		util \
 		conf \